Page 1276 - Small Animal Internal Medicine, 6th Edition

1248 PART XI Immune-Mediated Disorders

Numerous criteria for the diagnosis of SLE in dogs have clinicopathologic abnormalities suggestive of SLE. Only 1 of
been extrapolated from the literature in humans. The most 47 dogs tested that did not have any major signs of SLE had
VetBooks.ir commonly accepted and clinically applicable criteria are immune-mediated disease, and this dog was seronegative for
ANA. Ten (21%) of 47 dogs were seropositive for ANA.
shown in Table 73.8. Measurement of serum ANA titer is a
relatively sensitive test to confirm the diagnosis of SLE,
with SLE had immune-mediated disease, and ANA was posi-
although the sensitivity reported in the literature ranges Conversely, 13 of 16 dogs with two major signs compatible
from 50% to 100% (see Chapter 71). The variability in diag- tive in 10 of these dogs. These results emphasize that the
nostic sensitivity probably arises from variation in the diag- positive predictive value of a diagnostic test is lower in a
nostic criteria for confirming the diagnosis, as well as population of animals in which the disease prevalence is low.
variations in the populations of dogs tested. When used in The LE test is rarely used clinically for diagnosis of SLE
dogs that have appropriate clinical criteria for SLE, the ANA because of very low sensitivity. A number of other antibody
test is an excellent test; however, false-positive results can tests have been investigated in groups of dogs with SLE,
occur in dogs and cats with other inflammatory or infectious including antinative DNA antibodies, antiextractable nuclear
disorders or neoplasia. ANAs are detected in 10% to 20% of antigen antibodies, and antihistone antibodies. None of
dogs with seroreactivity to Bartonella vinsonii, E. canis, and these tests has been extensively evaluated in dogs, and none
Leishmania infantum. Dogs with seroreactivity to multiple is currently commercially available.
pathogens are more likely to be ANA positive. A recent study
of 120 dogs in which an ANA titer was measured empha- Treatment
sized the importance of appropriate patient selection for Immunosuppressive therapy for SLE begins with high doses
testing. In this study, measurement of an ANA titer was not of prednisone/prednisolone (1-2 mg/kg PO q12h). The dose
a useful diagnostic test in dogs without any major clinical or is then tapered if disease remission is achieved. Addition of

TABLE 73.8

Criteria for Diagnosis of SLE

MINIMUM DIAGNOSTIC TESTING
NECESSARY TO SUBSTANTIATE DIAGNOSTIC TEST NEEDED TO
MAJOR SIGNS MAJOR SIGN MINOR SIGNS SUBSTANTIATE

Polyarthritis Synovial fluid analysis and culture Fever of unknown Abdominal radiographs, urine
origin culture, no response to antibiotics
Dermatologic lesions Skin scraping, skin biopsy CNS signs CT or MRI scan, CSF tap with
(consistent with SLE) infectious disease serology
GN Urine protein/creatinine ratio >2, Oral ulceration Biopsy of lesions
renal biopsy useful but not required
Polymyositis Increased creatine kinase or muscle Lymphadenopathy Lymph node aspirate
biopsy demonstrating inflammation
Hemolytic anemia Regenerative anemia, positive Pericarditis Echocardiography
Coombs test, bone marrow
aspirate if anemia not
regenerative, negative infectious
disease testing
Immune-mediated Bone marrow aspirate, negative Pleuritis Thoracic radiographs,
thrombocytopenia infectious disease testing thoracocentesis
Immune-mediated Bone marrow aspirate, negative
leukopenia infectious disease testing

A diagnosis of SLE is considered confirmed if there are two major signs compatible with SLE and the antinuclear antibody (ANA) titer or LE
test is positive or if there is one major sign and two minor signs and the ANA test or LE test is positive. A diagnosis is considered probable if
there is only one major sign or two minor signs and a positive ANA titer (or LE test) or if there are two major signs and a negative ANA titer.
Immune-mediated hemolytic anemia in conjunction with immune-mediated thrombocytopenia (Evans syndrome) is not considered to be a
diagnosis of SLE unless there is an additional major or minor sign. Not all testing listed in the table is necessary in all cases. Specific
diagnostic tests will depend on the individual case presentation and geographic location.
CNS, Central nervous system; CSF, cerebrospinal fluid; CT, computed tomography; GN, glomerulonephritis; LE, lupus erythematosus; MRI,
magnetic resonance imaging; SLE, systemic lupus erythematosus.
Modified from Marks SL, Henry CJ: CVT update: diagnosis and treatment of systemic lupus erythematosus. In Bonagura JD, ed.: Kirk’s current
veterinary therapy XIII: small animal practice, ed 13, Philadelphia, 2000, WB Saunders, p 514.